Overexpression of miR‑145 in U87 cells reduces glioma cell malignant phenotype and promotes survival after in vivo implantation

The function of miR-145 in colorectal cancer progression; an updated review on related signaling pathways

MicroRNAs (miRNA) are a broad class of small, highly conserved non-coding RNAs that largely influence gene expression after transcription through binding to various target mRNAs. miRNAs are frequently dysregulated in a wide array of human cancers, possessing great value as diagnostic and therapeutic targets. miR-145, as promising tumor suppressor miRNA, also exhibits deregulated expression levels in human malignancies and participates in various processes, including cell proliferation, apoptosis, migration and differentiation. In particular, miR-145 has been shown to be downregulated in colorectal cancer (CRC), which in turn leads to cell growth, invasion, metastasis and drug resistance. Furthermore, miR-145 is involved in the regulation of multiple tumor specific signaling pathways, such as KRAS and P53 signaling by targeting various genes through colorectal tumorigenesis. Therefore, considering its diagnostic and therapeutic potential, it was aimed to present the recent finding focusing on miR-145 functions to better understand its involvement in CRC incidence and progression through interplay with various signaling pathways. This study is based on articles indexed in PubMed and Google scholar until 2021.

Angioregulatory role of miRNAs and exosomal miRNAs in glioblastoma pathogenesis

Glioblastoma (GB) is a highly aggressive cancer of the central nervous system, occurring in the brain or spinal cord. Many factors such as angiogenesis are associated with GB development. Angiogenesis is a procedure by which the pre-existing blood vessels create new vessels that play an essential role in health and disease, including tumors. Also, angiogenesis is one of the significant factors thought to be responsible for treatment resistance in many tumors, including GB. Hence, an improved understanding of the molecular processes underlying GB angiogenesis will pave the way for developing potential new treatments. Recently, it has been found that microRNAs (miRNAs) and exosomal miRNAs have a crucial role in inducing or inhibiting the angiogenesis process in GB development. A better knowledge of the miRNA's regulation pathway in the angiogenesis process in cancer offers unique mechanistic insight into the mechanism of tumor-associated neovascularization. Because of advancements in miRNA characterization and delivery methods, miRNAs can also be employed in clinical settings as potential biomarkers for anti-angiogenic treatment response as well as therapies targeting tumor angiogenesis. The recent finding and insights about miRNAs' angioregulatory role and exosomal miRNAs in GB are provided throughout the review. Also, we discuss the new concept of miRNAs-based therapies for GB in the future.

LINC00883 Promotes Drug Resistance of Glioma Through a microRNA-136/NEK1-Dependent Mechanism

Objective

Accumulating evidence has highlighted the roles of long noncoding RNAs (lncRNAs) as competing endogenous RNAs (ceRNAs) of microRNAs (miRNAs) through their binding sites in the progression of glioma. Hereby, we aim to explore the role of LINC00883 as a regulator of miR-136 and its target, NIMA-related kinase 1 (NEK1), thus, its involvement in the drug resistance of glioma cells.

Methods and Results

Mechanistic investigations by dual-luciferase reporter, RNA pull-down, and RNA-binding protein immunoprecipitation (RIP) assays indicated that LINC00883 bound to miR-136, thereby blocking miR-136-induced downregulation of NEK1. Through gain-of-function experiments in U251 cells that presented a high drug resistance, we found that ectopic expression of LINC00883 resulted in increased MRP (encoding multidrug resistance-associated protein), limited cell apoptosis, and increased proliferation. Expectedly, depleting LINC00883 yielded tumor-suppressive and anti-chemoresistance effects on U251 cells by increasing miR-136 and inhibiting NEK1. Next, drug-resistant glioma cell line SOWZ1, drug-sensitive glioma cell line SOWZ2, and drug-resistant glioma cell line SOWZ2-BCNU (SOWZ2 cultured in BCNU) were applied to validate the roles of LINC00883 in the regulation of multidrug resistance. LINC00883 knockdown suppressed the viability of SWOZ1, SWOZ2, and SWOZ2-BCNU cells.

Conclusion

In conclusion, LINC00883 knockdown reduces drug resistance in glioma. Hence, our study provides a future strategy to prevent drug resistance-induced therapeutic failure in glioma.

Roles of Non-coding RNAs and Angiogenesis in Glioblastoma

One of the significant hallmarks of cancer is angiogenesis. It has a crucial function in tumor development and metastasis. Thus, angiogenesis has become one of the most exciting targets for drug development in cancer treatment. Here we discuss the regulatory effects on angiogenesis in glioblastoma (GBM) of non-coding RNAs (ncRNAs), including long ncRNA (lncRNA), microRNA (miRNA), and circular RNA (circRNA). These ncRNAs may function in trans or cis forms and modify gene transcription by various mechanisms, including epigenetics. NcRNAs may also serve as crucial regulators of angiogenesis-inducing molecules. These molecules include, metalloproteinases, cytokines, several growth factors (platelet-derived growth factor, vascular endothelial growth factor, fibroblast growth factor, hypoxia-inducible factor-1, and epidermal growth factor), phosphoinositide 3-kinase, mitogen-activated protein kinase, and transforming growth factor signaling pathways.

Effect of MicroRNA145 on the multidrug resistance gene of ulcerative colitis in rats

Multidrug resistance gene (MDR1a) and P-glycoprotein (P-gp) play an important role in the development of ulcerative colitis (UC) and influence the therapeutic effect of glucocorticoids, which may lead to drug resistance mechanically. UC may be related to miR-145 to some extent, and the relationship still needs further exploration. In this study we found that the expression of miR-145 was downregulated in the colonic tissues of rats with Dextran sodium sulfate (DSS)-induced UC. Also, the expression of MDR1a in colon tissues of each group negatively correlated with the expression of miR-145 in rats. The change in the plasma peak concentration (Cmax) in each group positively related to the miR-145 level. Mechanistically, miR-145 negatively regulated the expression and function of P-gp via acting directly on the 3'-UTR of MDR1 mRNA. Overall, these results indicated that miR-145 had a protective effect on the colorectal mucosa, and its downregulation may enhance the expression and function of MDR1a and P-gp, promoting the occurrence and development of UC. The downregulation of miR-145 reduced the drug sensitivity of 5-aminosalicylic acid (5-ASA) and glucocorticoids in treating UC, indicating that miR-145 might be a potential therapeutic target for UC.

MicroRNAs involved in the EGFR pathway in glioblastoma

Glioblastoma (GBM) is the most common primary malignant tumor in adults, and its morbidity and mortality are very high. Although progress has been achieved in the treatment of GBM, such as surgery, chemotherapy and radiotherapy, in recent years, the prognosis of patients with GBM has not improved significantly. MicroRNAs (miRNAs) are endogenous noncoding single-stranded RNAs consisting of approximately 20-22 nucleotides that regulate gene expression at the posttranscriptional level by binding to target protein-encoding mRNAs. Notably, miRNAs regulate various carcinogenic pathways, one of which is the epidermal growth factor receptor (EGFR) signaling pathway, which controls cell proliferation, invasion, migration, angiogenesis and apoptosis. In this review, we summarize the novel discoveries of roles for miRNAs targeting the factors in the EGFR signaling pathway in the occurrence and development of GBM. In addition, we describe their potential roles as biomarkers for the diagnosis and prognosis of GBM and for determining the treatment resistance of GBM and the efficacy of therapeutic drugs.

Extracellular vesicles from human liver stem cells inhibit renal cancer stem cell-derived tumor growth in vitro and in vivo

Cancer stem cells (CSCs) are considered as responsible for initiation, maintenance and recurrence of solid tumors, thus representing the key for tumor eradication. The antitumor activity of extracellular vesicles (EVs) derived from different stem cell sources has been investigated with conflicting results. In our study, we evaluated, both in vitro and in vivo, the effect of EVs derived from human bone marrow mesenchymal stromal cells (MSCs) and from a population of human liver stem cells (HLSCs) of mesenchymal origin on renal CSCs. In vitro, both EV sources displayed pro‐apoptotic, anti‐proliferative and anti‐invasive effects on renal CSCs, but not on differentiated tumor cells. Pre‐treatment of renal CSCs with EVs, before subcutaneous injection in SCID mice, delayed tumor onset. We subsequently investigated the in vivo effect of MSC‐ and HLSC‐EVs systemic administration on progression of CSC‐generated renal tumors. Tumor bio‐distribution analysis identified intravenous treatment as best route of administration. HLSC‐EVs, but not MSC‐EVs, significantly impaired subcutaneous tumor growth by reducing tumor vascularization and inducing tumor cell apoptosis. Moreover, intravenous treatment with HLSC‐EVs improved metastasis‐free survival. In EV treated tumor explants, we observed both the transfer and the induction of miR‐145 and of miR‐200 family members. In transfected CSCs, the same miRNAs affected cell growth, invasion and survival. In conclusion, our results showed a specific antitumor effect of HLSC‐EVs on CSC‐derived renal tumors in vivo, possibly ascribed to the transfer and induction of specific antitumor miRNAs. Our study provides further evidence for a possible clinical application of stem cell‐EVs in tumor treatment.

What's new?

Stem cell‐derived extracellular vesicles (EVs) can reprogram target cells and promote tissue repair by transferring their cargo. However, the anti‐tumor activity of EVs derived from different stem cell sources has been investigated with conflicting results. Here, the authors demonstrate for the first time the anti‐tumor effect of EVs from human liver stem cells (HLSC‐EVs) in a systemic intravenous administration model. HLSC‐EVs had a selective effect on cancer stem cells that could be ascribed to the transfer and induction of anti‐tumor miRNAs. This study highlights the potential clinical use of stem cell‐derived EVs, alone or in combination with other cancer therapies.

HOXD-AS1/miR-130a sponge regulates glioma development by targeting E2F8

Glioma development is an extremely complex process with changes occurring in numerous genes. HOXD antisense growth-associated long noncoding RNA (HOXD-AS1), an important long noncoding RNA (lncRNA), is known to regulate metastasis-related gene expression in bladder cancer, ovarian cancer and neuroblastoma. Here, we elucidated the function and possible molecular mechanisms of lncRNA HOXD-AS1 in human glioma cells. Our results proved that HOXD-AS1 expression was upregulated in glioma tissues and in glioma cell lines. HOXD-AS1 overexpression promoted cell migration and invasion in vitro, whereas knockdown of HOXD-AS1 expression repressed these cellular processes. Mechanistic studies further revealed that HOXD-AS1 could compete with the transcription factor E2F8 to bind with miR-130a, thus affecting E2F8 expression. Additionally, reciprocal repression was observed between HOXD-AS1 and miR-130a, and miR-130a mediated the tumor-suppressive effects of HOXD-AS1 knockdown. Taken together, these results provide a comprehensive analysis of the role of HOXD-AS1 in glioma cells and offer important clues to understand the key roles of competing endogenous RNA (ceRNA) mechanisms in human glioma.

MiR-23a transcriptional activated by Runx2 increases metastatic potential of mouse hepatoma cell via directly targeting Mgat3

MicroRNAs (miRNAs) and aberrant glycosylation both play important roles in tumor metastasis. In this study, the role of miR-23a in N-glycosylation and the metastasis of mouse hepatocellular carcinoma (HCC) cells was investigated. The miRNA expression array profiles that were confirmed by qPCR and Western blot analyses revealed higher miR-23a expression levels in Hca-P cells (with lymphatic metastasis potential) than in Hepa1-6 cells (with no lymphatic metastasis potential), while the expression of mannoside acetylglucosaminyltransferase 3 (Mgat3) was negatively associated with metastasis potential. Mgat3 is a key glycosyltransferase in the synthesis of the bisecting (β1,4GlcNAc branching) N-glycan structure. Bioinformatics analysis indicated that Mgat3 may be a target of miR-23a, and this hypothesis was verified by dual-luciferase reporter gene assays. Furthermore, we found that the transcription factor Runx2 can directly bind to the miR-23a gene promoter and promote its expression, as shown in dual-luciferase reporter gene assays and ChIP assays. Collectively, these results indicate that miR-23a might increase the metastatic potential of mouse HCC by affecting the branch formation of N-glycan chains presented on the cell surface through the targeting of the glycosyltransferase Mgat3. These findings may provide insight into the relationship between abnormal miRNA expression and aberrant glycosylation during tumor lymphatic metastasis.

Transfer of functional microRNAs between glioblastoma and microvascular endothelial cells through gap junctions

Extensive invasion and angiogenesis are hallmark features of malignant glioblastomas. Here, we co-cultured U87 human glioblastoma cells and human microvascular endothelial cells (HMEC) to demonstrate the exchange of microRNAs that initially involve the formation of gap junction communications between the two cell types. The functional inhibition of gap junctions by carbenoxolone blocks the transfer of the anti-tumor miR-145-5p from HMEC to U87, and the transfer of the pro-invasive miR-5096 from U87 to HMEC. These two microRNAs exert opposite effects on angiogenesis in vitro. MiR-5096 was observed to promote HMEC tubulogenesis, initially by increasing Cx43 expression and the formation of heterocellular gap junctions, and secondarily through a gap-junction independent pathway. Our results highlight the importance of microRNA exchanges between tumor and endothelial cells that in part involves the formation of functional gap junctions between the two cell types.

Molecular and Genetic Determinants of Glioma Cell Invasion

A diffusely invasive nature is a major obstacle in treating a malignant brain tumor, "diffuse glioma", which prevents neurooncologists from surgically removing the tumor cells even in combination with chemotherapy and radiation. Recently updated classification of diffuse gliomas based on distinct genetic and epigenetic features has culminated in a multilayered diagnostic approach to combine histologic phenotypes and molecular genotypes in an integrated diagnosis. However, it is still a work in progress to decipher how the genetic aberrations contribute to the aggressive nature of gliomas including their highly invasive capacity. Here we depict a set of recent discoveries involving molecular genetic determinants of the infiltrating nature of glioma cells, especially focusing on genetic mutations in receptor tyrosine kinase pathways and metabolic reprogramming downstream of common cancer mutations. The specific biology of glioma cell invasion provides an opportunity to explore the genotype-phenotype correlation in cancer and develop novel glioma-specific therapeutic strategies for this devastating disease.